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AMD Catalyst vs. X.Org Radeon Driver 2D Performance

01-18-2009, 09:10 AM

Phoronix: AMD Catalyst vs. X.Org Radeon Driver 2D Performance

One of the common complaints about the ATI Catalyst Linux driver is slow 2D performance, but is this really the case? Does AMD's binary-only Linux driver have 2D performance issues that could actually make it run slower than the open-source driver developed by the X.Org community through specifications released by AMD? In this article we have run a total of 28 benchmarks looking squarely at the 2D performance between the Catalyst (fglrx) driver and the xf86-video-ati (Radeon) drivers on Ubuntu Linux.

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Xserver 1.6 has extremely improved EXA performance, fglrx wouldn't have a chance with that, especially with Composite/RENDER and who knows what will be when the UXA stuff merges to EXA with Xserver 1.7...

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I gotta say that with my radeon 4850 and fglrx (8.12) I do notice some strange 2D performance characteristics. Windows resizing is (really) fast, but dragging windows around tends to eat up a whole CPU core and lag my entire desktop (any other rendering going on, i.e. my cpu usage grapher, comes to a complete halt). I get the same thing with a radeon 3200 (IGP). Text rendering is so-so, it's fast and usable, but I do tend to have to wait a few seconds for things like 'dmesg' in an xterm.

It's a long way from xf86-video-ati with shadowfb, but there wasn't (isn't?) EXA support yet for r600+ in xf86-video-ati so I haven't really been able to compare real 2D accel.

It's interesting I think that 2D performance isn't much better with my radeon 3200 since it uses system memory which is supposed to be much faster, right? (or at least I thought that's what made shadowfb so fast)

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I don't use a composition manager, and have to use fglrx to get working X. Redrawing of windows when I switch virtual desktop is horribly slow. Running xcompmgr makes if a little bit faster, but then I get weird artifacts when playing movies using mplayer. (Without xcompmgr I "only" get shearing artifacts)

My second machine have an old Matrox Mystique card from 98 or so. In many ways X11 on that one performs much better than my HD3870.

I upgraded from a GeForce 6600 with wich I used nvidias very high quality binary driver. However even though fglrx is horrible I still hope that I made the right decision when buying ATI. In a few month I hope that the free drivers will have reached a usable state.

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Pretty interesting to look at. I think the results were inconclusive. The next step would be to actually look at applications where the differences have meaning and then you could make some value statements from there. I suppose it depends on which applications your running. I give the article an A+ though. It informs and it adds value to the discussion.

What I learned is that AMD Linux does not have 'perfect' 2D support. The obvious question is, how about Nvidia? How about Solaris and Apple? Do the professional class cards do any better, Quadro or FireGL?

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Can't say I'm really surprised. On one hand, fglrx has massive amounts of code. There's spots in our EXA where we have just said, "this could be accelerated, but not without a lot of spaghetti." fglrx is spaghetti.

On the other hand, fglrx has some known weaknesses. The pixmap test is the classic example, although there were a few others that pleasantly surprised me. Their handling of things when a compositor is enabled also sucks; I would bet that their test numbers would go down significantly if a compositor were enabled, although it's entirely possible that they've improved their compositing since then.]